Sound propagating diaphragm and hoop



July 23, 1935., R M. HiERs TfL SOUND PROPAGATING DIAPHRAGM AND HOOPOriginal Filed March 18, 1935 ATTORNEY.

Patented July 23, 1935 UNITED STATES PATENT OFFICE AND HOOP

Ralph H. Hiers .and Herbert A. Hiers, Granville,

Mass., assignors Granville, Mass., chusetts Application March 18,

to Noble and Cooley Company,

corporation of Massa- 1933, Serial No. 661,447

Renewed October 26, 1934 4 Claims.

rihis invention relates to improvements in sound propagating diaphragmsand is directed more particularly to improvements in the methods ofmaking certain parts of drums and other l sound instruments.

The principal objects of the invention are di rected to improvements inthe method of making a hoop having a head or rdiaphragm associatedtherewith so that the head is supported under tension by the hoop. Morein particular, the invention contemplates the provision -of a structurewherein the head or diaphragm which is of relatively non-rigid material4is secured to a hoop of more rigid material in a taut condition withoutliability of injury to the head or diaphragm.

In United States Letters Patent 1,783,843, there is shown a method ofassociating a diaphragm with a hoop but the method disclosed andstructure resulting therefrom has been found to be objectionable in manyinstances principally for the reason that the head is likely to beinjured or ruptured by the clamping means so that its function isimpaired.

According to this invention, we provide a novel method and structurewherein the diaphragm may be secured to and supported by a. hoop underthe desired tension or tautness without danger of injury thereto all tothe end that the head and hoop or ring may be associated to .provide aunitary structure at low cost.

Numerous objects and novel features of the invention will be apparentfrom the following description of the preferred form thereof which forpurposes of disclosure is illustrated in the accompanying drawingwherein:

Fig. 1 is a plan view of a drum hoop or ring having the novel featuresof the invention associated therewith. .1

Fig. 2 is an enlarged partial sectional view on the line 2 2 of Fig. 1.

Fig. 3 is a side elevational view of the structure shown in Fig. l.

' Fig. 4 is a sectional view similar to Fig. 2 showing the hoop beforeit is formed into diaphragm engaging and supporting relation, and

Fig. 5 is a. View similar to Fig. 2 showing a modified form of theinvention.

Referring now to the drawing more in detail the invention will be fullydescribed. It will be understood that the invention is adapted for broadapplication but will be described in connection with .the securing of asingle diaphragm to a hoop. The hoop and its associated diaphragm areadapted for use in connection with any sound producing structure.

(Cl. 84-41l) in Figure l there is shown a cylindrical hoop 2 whichserves as a support for and has associated therewith a diaphragm ordrumhead 4. This hoop 2 is preferably made from relatively thin metal orthe like with its ends suitably over- .5 lapped or joined in somemanner. As shown in Fig. the hoop, in its initial form, may have bothits upper and lower edges, or one of its edges turned as at 6 to providesmooth non-sharp rounding edges. It is at least preferable that the etge adjacent the diaphragm be turned either inwardly or outwardly toprotect the head 4. A retaining member 8 which is also cylindrical inform and which is preferably of some more or less yieldabie materialsuch as cardboard, thin metal 15 or the like, is provided to fit insidethe hoop 2.

The diaphragm or drum head 4 is of some more or less non-rigid materialwhich is resilient when taut, such as calf skin, cloth, paper,sheet-metal or the like, and has its peripheral edge portions 20inserted between the members 2 and 3. With the edges of the drum-headinserted between the member 8 and body of the hoop the crimped edges 6of the hoop are rolled inwardly or outwardly. Thus the rounding edges 6clamp the `diaphragm 25 or press on the member 8 and clamp the diaphragmagainst the main body of the hoop as shown in Fig. 2. Snares such as 3may be provided adjacent the diaphragm.

The upper marginal edge of the hoop 2 may 30 likewise be rounded so thatit abuts the member 8. If desired, sufficient pressure may be employedto cause the upper portion of the member 8 to be pressed against themain body of the hoop.

It will be noted that since the edges of the 35 hoop are rounded at 6that there is provided a rounding surface which brings up against themember 8 and over which the diaphragm lies. This rounding edge iscapable of pressing the diaphragm and other parts together, and ofpress- 40 ing against the main body of the hoop with equal pressurearound the hoop and thereby hold the diaphragm under the proper anddesired condition of uniform tautness. There are no sharp surfaces oredges impinging the diaphragm which 45 tend to injure or rupture it, andyet the diaphragm is securely clamped to the supporting hoop in such amanner that itis not readily displaced.

It will be appreciated that since the diaphragms are usually made frommaterials which are relatively thin, that they are susceptible topuncture and rupture when impinged by sharp or rough and uneven edges.It is these possibilities that are entirely obviated by rounding the 2edges of the hoop and whereby the diaphragm may be pressed and clampedto the hoop.

The modification of the invention shown in Fig. 5 will now be described.In this form of the invention, like the hoop 2, a hoop 2t! has at leastits lower marginal edge rounded as at 22. A retaining member 251 isprovided which, as in the former case, is cylindrical or ring-like to twithin the hoop 20. A supplemental ring-like member 26 is also providedwhich may be of relatively rigid material such as metal and at' leasthas its lower marginal edge rounded as at 2S.

The member 2G overlies the member 2li and a diaphragm indicated by 3Bhas its marginal portion extending between the member 20 and the member2li. The edge of the hoop which is rounded presses on the diaphragm 3Band causes it to bear against the member 26. In this way the diaphragmis securely clamped in place under the proper tension and is not onlyprotected against injury by the turned edge of the hoop but is disposedso that it is pressed against the suitably rounded surface 28 of themember 26.

From the foregoing it will be observed that the structure is arrangedand adapted to securely clamp the diaphragm to the hoop in such a waythat the diaphragm is not likely to be injured as it is or would bewhere sharp and possibly ragged edges are at the peripheral edges of thehoop.

According to varied forms of the invention, the marginal portion of thediaphragm may extend between the yieldable member 24 and the relativelyrigid member 26 or, as indicated at 3l, between the member 2G and thecylindrical member thereadjacent. It is a distinctive feature of theinvention that the structure may include either the relatively yieldablering-like member or the relatively rigid ring-like member alone or thetwo together, as may be desired. While the use of a yieldable retainingmember such as 2li tends to enhance the resonant tone of the diaphragmthe rigid member 2B reinforces the structure and permits the use of arelatively thinhoop 2li, which, as stated, is preferable.

In any event, by means of theinvention it is not only possible toproperly secure and support the diaphragm under the desired degree oftautness but, when necessary and desired `for the purposes of economicalmanufacture, it is possible to use relatively thinner and moreinexpensive material for the diaphragm, since, at the place where it isclamped to the hoop, itis not injuriously affected by the clamping edgesof the hoop.

Having described the invention inthe format present preferred, what itis desired to claim and ysecure by `Letters Patent of the United -Statesis:

1. A unitary hoop and diaphragm structure constituting a soundpropagating device comprising in combination, a circular hoop member ofa certain diameter formed from a band of relatively rigid sheet materialof a certain width, the said hoop member having its lower marginal edgeturned upon itself to provide a rounded surface and the upper and lowermarginal edge portions 4of the hoop at either side of the main body ofthe hoop being curved inwardly to provide upper and lower flanges withthe marginal edges thereof-dis'- posed ata distance from the bodyportion to provide spaces between said edges and said body portion, acircular hoop-like retaining member 'of less diameter than thefirst-named hoop member formed from a band of relatively yieldablematerial of less width than the first-named band and extending aroundthe inside of the rstnamed band and disposed concentrically thereof withits marginal edges extending into said spaces, and a diaphragm ofgreater diameter than the first-named hoop member having its marginaledge portions extending downwardly over the said lower flange betweenthe rounded surface thereof and said retaining member and upwardlybetween said retaining member and the main body of the hoop, the saidrounded surface of the hoop member bearing on said diaphragm whereby themarginal edge portions of the diaphragm are clamped by said roundedsurface, said retaining member and said main body of the hoop in asound-propagating relation. v

2. A unitary hoop and diaphragm structure constituting a soundpropagating device comprisn ing in combination, a circular hoop memberof a certain diameter formed from a band ofrelatively rigid sheetmaterial of a certain width, the said hoop member having its lowermarginal edge turned upon itself to provide a rounded surface and theupper and lower marginal yedge portions of the hoop at either side ofthe main body of the hoop being curved inwardly to provide upper andlower flanges with the marginal edges thereof disposed at a distancefrom the body portion to provide spaces between said edges and said bodyportion, a circular hoop-like retaining member of less diameter than thefirst-named hoop member formed from a band of relatively rigid sheetmaterial of less width than the first-named band and extending aroundthe inside of the first-named band and disposed concentrically thereofwith its marginal edges extending int-o said spaces, said retainingmember having its lower marginal edge turned upon itself to provide arounded surface, and a diaphragm of greater diameter than thefirst-named hoop member havits marginal edge portions extendingdownwardly over the said lower flange between the rounded surfacethereof and said retaining member and upwardly between said retainingmember and the main body of the hoop, the said rounded surface of thehoop member bearing on said diaphragm whereby the marginal edge portionsof the diaphragm are clamped by said rounded surface, said retainingmember and said main body of the hoop in a sound-propagating relation.

3. A unitary hoop and diaphragm structure constituting a soundpropagating device comprising in combination, a circular hoop member ofa certain diameter formed from a band of relatively rigid sheet materialof a certain width, the said hoop member having its lower Amarginal edgeturned upon itself to provide a rounded surface and the upper and lowermarginal edge portions of the hoop at either side of the main body ofthe hoop being curved inwardly to provide upper and lower flanges withthe marginalv edges thereof disposed at a distance from the body portionto provide spaces between said edges and said body portion, a circularhoop-like retaining member of less diameter than the first-named hoopmember formed from a band of relatively rigid sheet material of lesswidth than the first-named band extending around the inside of thefirst-named band and disposed conoentrically thereof with its marginaledges extending into said spaces and having its lower marginal edgeturned upon itself to provide a rounded surface, a second circularhoop-like retaining member of less diameter than the first-named hoopmember formed from a band of relatively yieldable material of less widththan the first-named band disposed concentrically of said hoop memberbetween the main body portion of the hoop and the first-named retainingmember with its marginal edges extending into said spaces, and adiaphragm of greater diameter than the first-named hoop member havingits marginal edge portions extending downwardly over the said lowerflange between the rounded surface thereof and said rigid retainingmember and upwardly between said retaining members, the said roundedsurface of the hoop member bearing on said surface, said retainingmembers and the main body of the hoop in a sound-propagating relation.

4. A unitary hoop and diaphragm structure constituting a soundpropagating device comprising in combination, a circular hoop member ofa certain diameter formed from a band of relatively rigid sheet materialof a certain width, the said hoop member having its lower marginal edgeturned upon itself to provide a rounded surface and the upper and lowermarginal edge portions of the hoop at either side of the main body ofthe hoop being curved inwardly to provide upper and lower flanges withthe marginal edges thereof disposed at a distance from the body portionto provide spaces between said edges and said body portion, a circularhoop-like retaining member of less diameter than the first-named hoopmember formed from a band of relatively rigid sheet material of lesswidth than the first-named band extending around the inside of thefirst-named band and disposed concentrically thereof with its marginaledges extending into said spaces and having its lower marginal edgeturned upon itself to provide a rounded surface, a second circularhoop-like retaining member of less diameter than the first-named hoopmember formed from a band of relatively yieldable material of less widththan the first-narned band disposed concentrically of said hoop memberbetween the main body portion of the hoop and the first-named retainingmember with its marginal edges extending into said spaces, and adiaphragm of greater diameter than the first-named hoop member havingits marginal edge portions extending downwardly over the said lowerflange between the rounded surface thereof and said rigid retainingmember and upwardly between said yieldable retaining member and saidmain body of the hoop, the said rounded surface 20 of the hoop memberbearing on said diaphragm whereby the marginal edge portions of thediaphragm are clamped by said rounded surface, said retaining membersand the main body of the hoop in a sound-propagating relation.

RALPH H. HIERS. HERBERT A. HIERS

